LTC1981/LTC1982
Single and Dual Micropower
High Side Switch Controllers
in SOT-23
FEATURES
s
s
DESCRIPTIO
s
s
s
s
s
s
s
s
No External Components Required
Internal Voltage Triplers Produce High Side
Gate Drive for Logic Level FETs
Ultralow Power:
10µA Per Driver ON Current (LTC1982)
20µA ON Current (LTC1981)
<1µA Shutdown Current
V
CC
Range: 1.8V to 5V
Gate Drive Outputs Driven to Ground During
Shutdown
Gate Drive Outputs Internally Clamped to 7.5V Max
“Gate Drive Ready” Output (LTC1981)
Ultrasmall Application Circuit
5-Pin SOT-23 Package (LTC1981)
6-Pin SOT-23 Package (LTC1982)
The LTC
®
1981/LTC1982 are low-power, self-contained
N-channel MOSFET drivers. An internal voltage tripler
allows gates to be driven without the use of any external
components. Internal regulation circuitry allows quies-
cent current to drop to 10µA per driver (20µA for LTC1981)
once the gates are charged.
Low quiescent current and low shutdown current (under
1µA) make these parts ideal for battery and other power
constrained systems. The wide input voltage range ac-
commodates a variety of battery/input configurations.
Gate drive is internally clamped to 7.5V providing protec-
tion to the external MOSFET gate. The MOSFETs can be
driven in either high side or low side mode.
The LTC1981 single driver version also includes a gate
drive ready pin and twice the drive current capacity of the
dual driver LTC1982.
The LTC1981 is available in a 5-pin SOT-23. The LTC1982
is available in a 6-pin SOT-23.
, LTC and LT are registered trademarks of Linear Technology Corporation.
APPLICATIO S
s
s
s
Cellular Telephones
Portable POS Terminal
Handheld Battery Powered Equipment
TYPICAL APPLICATIONS
Single High Side Switch Controller
V
CC
1.8V TO 5.0V
Dual High Side Switch Controller
V
CC
1.8V TO 5.0V
+
10µF
Q1
Si3442DV
+
10µF
6
V
CC
5
LTC1982
SHDN 1
1
SHDN 1
GND
2
SHDN 2
3
4
5
V
CC
100k
GDR
GATE
DRIVE
READY
SHDN
1
LTC1981
GND
2
4
GATE
LOAD
SHDN
3
1981/82 TA01
SHDN 2
U
Q1
1/2 Si6925DQ
Q2
1/2 Si6925DQ
GATE 1 GATE 2
LOAD 1
LOAD 2
1981/82 TA02
U
U
1
LTC1981/LTC1982
ABSOLUTE
AXI U RATI GS
Terminal Voltage
LTC1981: V
CC
, GATE, SHDN, GDR ........ –0.3V to 7.5V
LTC1982: V
CC
, GATE 1, GATE 2,
SHDN 1, SHDN 2 ................... –0.3V to 7.5V
PACKAGE/ORDER I FOR ATIO
TOP VIEW
GDR 1
GND 2
SHDN 3
4 GATE
5 V
CC
ORDER PART
NUMBER
LTC1981ES5
S5 PART
MARKING
LTSF
SHDN 1 1
GND 2
SHDN 2 3
S5 PACKAGE
5-LEAD PLASTIC SOT-23
T
JMAX
= 150°C,
θ
JA
= 250°C/W
Consult factory for parts specified with wider operating temperature ranges.
The
q
denotes the specifications which apply over the full operating
temperature range, otherwise specifications are at T
A
= 25°C. V
CC
= 5V unless otherwise specified. C
GATE 1
= C
GATE 2
= C
GATE
= 1000pF.
SYMBOL
V
CC
I
CC
PARAMETER
Operating Supply Voltage
Supply Current
GATE 1 and GATE 2 Outputs High
GATE 1 or GATE 2 Outputs High
GATE Output High (LTC1981)
SHDN 1 and SHDN 2 Inputs Low
SHDN Input Low (LTC1981)
V
CC
= 1.8V
V
CC
= 2.7V
V
CC
= 3.3V
V
CC
= 5V
Measured with 10k Resistor from Output to GND
From SHDN 1, SHDN 2 Going High to
GATE 1, GATE 2 = V
CC
+ 1V
From SHDN Going High to GATE = V
CC
+1V (LTC1981)
t
OFF
V
IL
V
IH
C
IN
I
IN
Turn-off Time into 1000pF
SHDN Input Low Voltage
SHDN Input High Voltage
SHDN Input Capacitance
SHDN Input Leakage Current
From SHDN 1, SHDN 2 Going Low to
GATE 1, GATE 2
,
GATE = 100mV
V
CC
= 1.8V to 5.5V
V
CC
= 1.8V to 5.5V
(Note 4)
q
q
ELECTRICAL CHARACTERISTICS
CONDITIONS
I
SHDN
V
GATE
SHDN Supply Current
GATE Drive Output Voltage
f
OSC
t
ON
Charge Pump Oscillator Frequency
Turn-on Time into 1000pF
2
U
U
W
W W
U
W
(Notes 1, 2)
Operating Temperature Range
LTC1981E/LTC1982E (Note 3) ............ – 40°C to 85°C
Storage Temperature Range ................. – 65°C to 150°C
Lead Temperature (Soldering, 10 sec).................. 300°C
TOP VIEW
6 V
CC
5 GATE 1
4 GATE 2
ORDER PART
NUMBER
LTC1982ES6
S6 PART
MARKING
LTPF
S6 PACKAGE
6-LEAD PLASTIC SOT-23
T
JMAX
= 150°C,
θ
JA
= 230°C/W
MIN
q
q
q
q
q
q
q
q
q
q
TYP
17
10
17
MAX
5.5
30
20
30
1
1
UNITS
V
µA
µA
µA
µA
µA
V
V
V
V
kHz
µs
µs
µs
V
1.8
4.27
6.40
6.90
6.90
4.50
6.75
7.25
7.25
600
110
85
12
4.75
7.10
7.50
7.50
0.4
1.6
5
±1
V
pF
µA
LTC1981/LTC1982
The
q
denotes the specifications which apply over the full operating
temperature range, otherwise specifications are at T
A
= 25°C. V
CC
= 5V unless otherwise specified. C
GATE 1
= C
GATE 2
= C
GATE
= 1000pF.
(LTC1981 only)
SYMBOL
V
OL
PARAMETER
GDR Output Voltage Low
GATE Drive Ready Trip Point
CONDITIONS
I
SINK
= 100µA, V
CC
= 1.8V
GATE Voltage Rising
V
CC
= 1.8V
V
CC
= 2.7V
V
CC
= 3.3V
V
CC
= 5V
GATE Voltage Falling
After GATE is Above the GDR Trip Threshold
10k Pull-Up to V
CC
q
q
q
q
q
ELECTRICAL CHARACTERISTICS
MIN
TYP
0.05
MAX
0.4
4.25
6.38
6.82
6.82
UNITS
V
V
V
V
V
%
µs
3.85
5.78
6.17
6.17
4.05
6.08
6.5
6.5
2
2
GDR Hysteresis
GDR Delay
Note 1:
Absolute Maximum Ratings are those values beyond which the life
of a device may be impaired.
Note 2:
All voltage values are with respect to GND.
Note 3:
the LTC1982E is guaranteed to meet performance specifications
from 0°C to 70°C. Specifications over the –40°C to 85°C operating
temperature range are assured by design, characterization and correlation
with statistical process controls.
Note 4:
Guaranteed by design not subject to test.
TYPICAL PERFOR A CE CHARACTERISTICS
GATE Drive Voltage vs Supply
Voltage
8.0
7.5 T
A
= 25°C
7.0
GATE DRIVE VOLTAGE
6.5
(V
GS
COMMON SOURCE)
6.0
5.5
5.0
4.5
4.0
3.5
3.0
2.5
GATE DRIVE –V
CC
2.0
(V
GS
SOURCE FOLLOWER)
1.5
1.0
0.5
0
1.5 2.0 2.5 3.0 3.5 4.0 4.5 5.0
SUPPLY VOLTAGE, V
CC
(V)
GATE DRIVE CURRENT (µA)
GATE DRIVE VOLTAGE (V)
SUPPLY CURRENT (µA)
I
SUPPLY
60
50
SUPPLY CURRENT (µA)
SUPPLY CURRENT (µA)
T
A
= 25°C
V
CC
= 3V
SHDN1 TIED
TO SHDN2
40
30
20
10
0
0
1
SHDN LOGIC INPUT VOLTAGE (V)
U W
1982 G01
Supply Current vs Supply Voltage
25
T
A
= 25°C
20
LTC1981 OR
BOTH CHANNELS ON
LTC1982
EITHER CHANNEL ON
LTC1982
100
GATE Drive Current (LTC1982)
V
CC
= 3.3V
V
CC
= 2.7V
V
CC
= 1.8V
10
V
CC
= 5V
15
10
1
5
0
5.5
0.1
1.0 1.5 2.0 2.5 3.0 3.5 4.0 4.5 5.0 5.5
SUPPLY VOLTAGE (V)
1982 G02
T
A
= 25°C
0
1
2
3
4
5
6
GATE DRIVE VOLTAGE (V)
7
8
1982 G03
I
SUPPLY
300
250
200
150
100
50
0
T
A
= 25°C
V
CC
= 5V
SHDN1 TIED
TO SHDN2
2
0
1
SHDN LOGIC INPUT VOLTAGE (V)
2
1981/82 G04
1981/82 G05
3
LTC1981/LTC1982
TYPICAL PERFOR A CE CHARACTERISTICS
Turn-On Time (LTC1982)
400
350
TURN-ON TIME (µs)
C
GATE
= 1000pF
T
A
= 25°C
TURN-OFF TIME (µs)
300
250
200
150
100
50
V
GS
= 1V
V
GS
= 2V
30
25
20
15
10
5
0
1.5 2.0 2.5 3.0 3.5 4.0 4.5 5.0 5.5 6.0
SUPPLY VOLTAGE (V)
1982 G07
GATE DRIVE VOLTAGE (V)
0
1.5 2.0 2.5 3.0 3.5 4.0 4.5 5.0 5.5 6.0
SUPPLY VOLTAGE (V)
1982 G06
GATE Drive Current (LTC1981)
100
V
CC
= 2.7V
V
CC
= 1.8V
10
V
CC
= 5V
V
CC
= 3.3V
GATE DRIVE CURRENT (µA)
200
150
100
50
V
GS
= 1V
TURN-OFF TIME (µs)
TURN-ON TIME (µs)
1
0.1
0
1
2
3
4
5
6
GATE DRIVE VOLTAGE (V)
7
8
PIN FUNCTIONS
LTC1981:
GDR (Pin 1):
Gate Drive Ready Active High Open Drain
Output. Used to indicate when the gate drive output is
greater than 90% of its final value.
GND (Pin 2):
Ground.
SHDN (Pin 3):
SHDN Active Low Input. Used to shut down
the part and force the GATE output pin to ground.
GATE (Pin 4):
Gate Drive Output to an External High Side
Switch. Fully enhanced by internal charge pump. Con-
trolled by the SHDN input pin. Output voltage on this pin
will be approximately 2.5 times V
CC
or 7.25V, whichever is
less.
V
CC
(Pin 5):
Input Supply Voltage. Range from 1.8V to
5.5V.
LTC1982:
SHDN 1 (Pin 1):
SHDN 1 Active Low Input. Used to shut
down the GATE 1 charge pump and force the GATE 1
output pin to ground.
GND (Pin 2):
Ground.
SHDN 2 (Pin 3):
SHDN 2 Active Low Input. Used to shut
down the GATE 2 charge pump and force the GATE 2
output pin to ground.
4
U W
1981/82 G09
Turn-Off Time (LTC1982)
40
35
C
GATE
= 1000pF
T
A
= 25°C
TIME FOR V
GATE
< 0.1V
7.50
7.45
7.40
7.35
7.30
7.25
7.20
7.15
7.10
7.05
GATE Drive Voltage vs
Temperature
V
CC
= 3.3V
7.00
– 60 – 40 – 20 0 20 40 60
TEMPERATURE (°C)
80
100
1982 G08
Turn-On Time (LTC1981)
300
250
V
GS
= 2V
C
GATE
= 1000pF
T
A
= 25°C
25
Turn-Off Time (LTC1981)
C
GATE
=1000pF
T
A
= 25°C
TIME FOR V
GATE
< 0.1
20
15
10
5
0
0
1.5 2.0 2.5 3.0 3.5 4.0 4.5 5.0 5.5 6.0
SUPPLY VOLTAGE (V)
1981/82 G10
1.5 2.0 2.5 3.0 3.5 4.0 4.5 5.0 5.5 6.0
SUPPLY VOLTAGE (V)
1981/82 G11
U
U
U
LTC1981/LTC1982
PIN FUNCTIONS
GATE 2(Pin 4):
Gate Drive Output to an External High Side
Switch. Fully enhanced by internal charge pump. Con-
trolled by the SHDN 2 input pin. Output voltage on this pin
will be approximately 2.5 times V
CC
or 7.25V, whichever is
less.
GATE 1 (Pin 5):
Gate Drive Output to an External High Side
Switch. Fully enhanced by internal charge pump. Con-
trolled by the SHDN 1 input pin. Output voltage on this pin
will be approximately 2.5 times V
CC
or 7.25V, whichever is
less.
V
CC
(Pin 6):
Input Supply Voltage. Range from 1.8V to 5.5V.
BLOCK DIAGRA SM
LTC1981 Single High Side Switch Driver
SHDN
REGULATING
EN CHARGE PUMP
15k
GATE
+
V
CC
–
+
–
REF
OPERATIO
Charge Pump
To fully enhance the external N-channel switches, internal
charge pumps are used to boost the output gate drive to
approximately 2.5 times the supply voltage, or 7.25V,
whichever is less. A feedback network is used to regulate
the output gate drive. This keeps the supply current low in
addition to providing a maximum output voltage limit. The
reason for the maximum output voltage limit is to avoid
switch gate source breakdown due to excessive gate
overdrive.
The gate drive outputs (GATE 1, GATE 2, or GATE) are
controlled by the shutdown input pins (SHDN 1, SHDN 2
or SHDN). A logic high input on one of the shutdown input
pins enables the corresponding charge pump and drives
W
U
U
U
U
LTC1982 Dual High Side Switch Driver
SHDN 1
EN
REGULATING
CHARGE
PUMP 1
30k
GATE 1
GDR
SHDN 2
EN
REGULATING
CHARGE
PUMP 2
30k
GATE 2
1981/82 BD02
1981/82 BD01
the related gate drive output pin high. A logic low input on
one of the shutdown input pins disables the correspond-
ing charge pump and drives the related gate drive output
pin low. If shutdown input on the LTC1981 is low or both
of the shutdown input pins on the LTC1982 are low, the
part will be placed into a low current shutdown mode
(<1µA).
Gate Drive Ready (LTC1981 Only)
The gate drive ready pin (GDR) is used to indicate when the
gate drive output (GATE) is greater than 90% of its final
value. This can be useful in applications that require
knowledge of the state of the gate drive for initialization
purposes or as fault detection should something be load-
ing the gate drive down.
5
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